如果在asp.net上发现重复，则标签不显示
本文关键字：标签 显示 asp net 发现 如果 | 更新日期: 2023-09-27 18:26:23
从数据库检索值时，我会检查文本框的值是否包含在数组中。数组包含从数据库中检索到的值。如果它确实包含值，那么它应该显示一个标签。这一直有效，直到我在if语句中添加了一个else，之后标签就拒绝显示了。
主页：
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:MultiView ID="ManageCourseMultiView" ActiveViewIndex="1" runat="server">
<asp:View ID="OptionsView" runat="server">
<asp:LinkButton ID="CourseLinkButton" CommandName="SwitchViewByID" CommandArgument="ManageCourseView" runat="server">Please click here to manage your course.</asp:LinkButton>
<asp:LinkButton ID="CourseContentLinkButton" CommandName="SwitchViewByID" CommandArgument="ManageCourseContentView" runat="server">Please click here to manage your course content.</asp:LinkButton>
<asp:HyperLink ID="CreateCourseLink" NavigateUrl="~/Instructors/CreateCourse2.aspx" runat="server">Please click here to create a course.</asp:HyperLink>
<br />
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:DefaultConnection %>" SelectCommand="SELECT * FROM [Course] WHERE ([CourseId] = @CourseId)">
<SelectParameters>
<asp:ControlParameter ControlID="GridView1" Name="CourseId" PropertyName="SelectedValue" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
</asp:View>
<asp:View ID="ManageCourseView" runat="server">
<asp:Label ID="UserIdLabel" Visible="true" runat="server" Text="Label"></asp:Label>
<asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True" OnSelectedIndexChanged="GridView1_SelectedIndexChanged" AutoGenerateColumns="False" DataKeyNames="CourseId" DataSourceID="GridViewSource" Width="1072px">
<Columns>
<asp:CommandField ShowSelectButton="True" />
<asp:BoundField DataField="CourseId" HeaderText="CourseId" InsertVisible="False" ReadOnly="True" SortExpression="CourseId" />
<asp:BoundField DataField="CourseName" HeaderText="CourseName" SortExpression="CourseName" />
<asp:BoundField DataField="ForRole" HeaderText="ForRole" SortExpression="ForRole" />
<asp:CheckBoxField DataField="Certification" HeaderText="Certification" SortExpression="Certification" />
<asp:BoundField DataField="UserId" Visible="false" HeaderText="UserId" SortExpression="UserId" />
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="GridViewSource" runat="server" ConnectionString="<%$ ConnectionStrings:DefaultConnection %>" SelectCommand="SELECT Course.* FROM Course WHERE (UserId = @UserId)">
<SelectParameters>
<asp:ControlParameter ControlID="UserIdLabel" Name="UserId" PropertyName="Text" />
</SelectParameters>
</asp:SqlDataSource>
<br />
<table>
<tr>
<td>
<asp:Label ID="CourseEditName" runat="server" Text="Course Name:"></asp:Label>
</td>
<td>
<asp:TextBox ID="CourseEditNameTextBox" runat="server"></asp:TextBox>
<asp:Label ID="nameerror" runat="server" ForeColor="Red" Visible="false" Text="This Coursename already exists, please enter another one."></asp:Label>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" Display="Dynamic" ForeColor="Red" ControlToValidate="CourseEditNameTextBox" ErrorMessage="Course Name cannot be empty."></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td>
<asp:Label ID="CourseEditForRoles" runat="server" Text="For Role: "></asp:Label>
</td>
<td>
<asp:DropDownList ID="CourseEditForRole" runat="server">
<asp:ListItem Text="Parent" Value="Parent"></asp:ListItem>
<asp:ListItem Text="Staff" Value="Staff"></asp:ListItem>
<asp:ListItem Text="Health Care PRofessional" Value="HealthPro"></asp:ListItem>
</asp:DropDownList>
<asp:SqlDataSource ID="ForRoleUpdate" runat="server" ConnectionString="<%$ ConnectionStrings:DefaultConnection %>" SelectCommand="SELECT RoleName FROM Roles WHERE (RoleName <> 'BackOffice') AND (RoleName <> 'Instructor')"></asp:SqlDataSource>
</td>
</tr>
<tr>
<td>
<asp:Label ID="CourseEditCertification" runat="server" Text="Certification: "></asp:Label>
</td>
<td>
<asp:CheckBox ID="CourseEditCertificationCheckBox" runat="server" />
</td>
</tr>
<tr>
<td>
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label2" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label3" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label4" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label5" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label6" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label7" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label8" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label9" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label10" runat="server" Text="Label"></asp:Label>
<asp:Label ID="Label11" runat="server" Text="Label"></asp:Label>
</td>
<td>
<asp:Button ID="CourseEditUpdate" OnClick="CourseEditUpdate_Click" runat="server" Text="Finish Editing" />
<asp:Button ID="CourseEditCancel" runat="server" CommandName="Cancel" CausesValidation="false" Text="Cancel" />
</td>
</tr>
</table>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:DefaultConnection %>" DeleteCommand="DELETE FROM [Course] WHERE [CourseId] = @CourseId" InsertCommand="INSERT INTO [Course] ([CourseName], [ForRole], [Certification], [UserId]) VALUES (@CourseName, @ForRole, @Certification, @UserId)" SelectCommand="SELECT * FROM [Course]" UpdateCommand="UPDATE [Course] SET [CourseName] = @CourseName, [ForRole] = @ForRole, [Certification] = @Certification, [UserId] = @UserId WHERE [CourseId] = @CourseId">
<DeleteParameters>
<asp:Parameter Name="CourseId" Type="Int32" />
</DeleteParameters>
<InsertParameters>
<asp:Parameter Name="CourseName" Type="String" />
<asp:Parameter Name="ForRole" Type="String" />
<asp:Parameter Name="Certification" Type="Boolean" />
<asp:Parameter Name="UserId" Type="Object" />
</InsertParameters>
<UpdateParameters>
<asp:Parameter Name="CourseName" Type="String" />
<asp:Parameter Name="ForRole" Type="String" />
<asp:Parameter Name="Certification" Type="Boolean" />
<asp:Parameter Name="UserId" Type="Object" />
<asp:Parameter Name="CourseId" Type="Int32" />
</UpdateParameters>
</asp:SqlDataSource>
</asp:View>
<asp:View ID="ManageCourseContentView" runat="server">
<h2>Test</h2>
</asp:View>
</asp:MultiView>
</ContentTemplate>
</asp:UpdatePanel>
CodeBhind:
protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
Boolean checkboxvalue;
string cert;
using (var connection = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString))
{
connection.Open();
using (var command = connection.CreateCommand())
{
command.CommandText = "SELECT * FROM Course WHERE CourseId = '" + GridView1.SelectedValue.ToString() + "'";
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
CourseEditForRole.SelectedValue = reader["ForRole"].ToString();
CourseEditNameTextBox.Text = reader["CourseName"].ToString();
checkboxvalue = Convert.ToBoolean(reader["Certification"]);
cert = reader["Certification"].ToString();
if (cert == "False")
{
CourseEditCertificationCheckBox.Checked = false;
}
else
{
CourseEditCertificationCheckBox.Checked = true;
}
}
}
}
using (var command = connection.CreateCommand())
{
command.CommandText = "SELECT CourseName FROM Course WHERE (CourseId = '" + GridView1.SelectedValue.ToString() + "')";
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
coursenamevalue = reader["CourseName"].ToString();
}
}
}
using (var command2 = connection.CreateCommand())
{
command2.CommandText = "SELECT CourseName FROM [Course] WHERE (CourseName <> '" + coursenamevalue + "')";
using (var reader = command2.ExecuteReader())
{
int i = 0;
while (reader.Read())
{
coursename[i] = reader["CourseName"].ToString();
i++;
}
counter = i;
}
}
}
}
protected void CourseEditUpdate_Click(object sender, EventArgs e)
{
Boolean checkboxvalue;
string cert;
using (var connection = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString))
{
connection.Open();
using (var command2 = connection.CreateCommand())
{
command2.CommandText = "SELECT CourseName FROM [Course] WHERE (CourseName <> '" + coursenamevalue + "')";
using (var reader = command2.ExecuteReader())
{
int i = 0;
while (reader.Read())
{
coursename[i] = reader["CourseName"].ToString();
if (CourseEditNameTextBox.Text.Equals(reader["CourseName"].ToString(), StringComparison.Ordinal))
{
//cameerror.Visible = true;
}
i++;
}
counter = i;
}
}
}
int k = 0;
while(!String.IsNullOrEmpty(coursename[k]))
{
if (coursename[k].Contains(CourseEditNameTextBox.Text))
{
nameerror.Visible = true;
}
else
{
nameerror.Visible = false;
}
k++;
}
}
问题是你继续while循环，如果它存在，你需要打破循环，因为数组中的最后一项不同，那么标签的文本框内容就会消失，你必须这样做：
int k = 0;
while(!String.IsNullOrEmpty(coursename[k]))
{
if (coursename[k].Contains(CourseEditNameTextBox.Text))
{
nameerror.Visible = true;
Break;
}
else
{
nameerror.Visible = false;
}
k++;
}